Defining a TCP/IP generic resource group for MSC

A TCP/IP generic resource group is defined for MSC by coding the GENIMSID parameter in both the IMS DFSDCxxx PROCLIB member and in the IMS Connect HWSCFGxx PROCLIB member.

Prerequisite: The following steps assume that the general system definition is already complete for IMS, IMS Connect, and the Structured Call Interface. These steps also do not cover the definition of MSC logical links, which is the same whether or not you are using TCP/IP generic resources.

The GENIMSID parameter defines a shared IMS ID that represents a group of IMS systems as a single IMS system. The MSC TCP/IP physical links that connect to a TCP/IP generic resource group specify the shared generic IMS ID of the TCP/IP generic resource group instead of specifying an IMS ID of a specific local IMS system.

TCP/IP generic resource links and non-generic TCP/IP physical links cannot coexist between the same two IMS systems. If a local IMS system is already linked to a remote IMS system by one or more non-generic TCP/IP physical links, the remote IMS system cannot connect to the local IMS system through a TCP/IP generic resource group.

Each MSC TCP/IP connection between a TCP/IP generic resource group and an outside IMS system is managed in the IMSplex by a single IMS Connect instance. MSC TCP/IP generic resources do not support the use of multiple IMS Connect instances to support the same MSC TCP/IP connection within the same MSC TCP/IP generic resource group.

Up to 936 IMS systems in an IMSplex can participate in an MSC TCP/IP generic resource group.

To define a TCP/IP generic resource group for an MSC TCP/IP connection:

Procedure

In the DFSDCxxx PROCLIB member of each participating IMS system in the IMSplex, specify a shared generic IMS ID on the GENIMSID parameter.
For example, GENIMSID=IMS.
In each IMS system in the TCP/IP generic resource group, code an MSPLINK system definition macro statement for each MSC TCP/IP physical link that will connect to the group.
Specify an ID for the physical link on the LCLPLKID parameter. Specify the ID of the local IMS Connect instance on the LCLICON parameter. All other MSPLINK parameters are specified the same as a TCP/IP physical link in a non-generic resources environment.

In non-XRF systems, except for the LCLPLKID parameter, the MSPLINK macros for the same physical link must be identical in each IMS system in the TCP/IP generic resource group. In XRF systems, the MSPLINK statement that defines a physical supported by an XRF pair would be identical in each IMS system in the XRF pair.
For example, in TCP/IP generic resource group with two non-XRF IMS systems, IMS1 and IMS2, the MSPLINK macro in IMS1 might be defined as:
```
PLNK13TA MSPLINK
         NAME=IMS3,
         LCLICON=HWS1,
         LCLPLKID=MSC13,
         TYPE=TCPIP,
         SESSION=2
```
In IMS2, the MSPLINK macro would be almost identical, except the LCLPLKID value would be different. For example:
```
PLNK13TA MSPLINK
         NAME=IMS3,
         LCLICON=HWS1,
         LCLPLKID=MSC23,
         TYPE=TCPIP,
         SESSION=2
```
In the HWSCFGxx PROCLIB member of the IMS Connect instance that supports the TCP/IP generic resource group, define an MSC configuration statement for each MSPLINK statement for each physical link in the TCP/IP generic resource group.
If you are using XRF, you can define a single MSC statement for a physical link that is used, alternately, by both IMS systems in the XRF pair. If you are not using XRF, you must define a separate MSC statement for each MSPLINK.

In each MSC configuration statement, specify the same ID for the physical link on the LCLPLKID parameter that you specified on the LCLPLKID parameter of the corresponding MSPLINK macro statement.

For example, for the MSPLINK statements defined for the non-XRF systems IMS1 and IMS2 in the previous step, the following MSC statements might be defined in the local IMS Connect:
```
MSC=(LCLPLKID=MSC13,RMTPLKID=MSC,LCLIMS=(IMS1),RMTIMS=IMS3,GENIMSID=IMS)
MSC=(LCLPLKID=MSC13,RMTPLKID=MSC,LCLIMS=(IMS2),RMTIMS=IMS3,GENIMSID=IMS)
```
However, if IMS1 and IMS2 were instead an XRF pair, the following MSC statement would be valid:
```
MSC=(LCLPLKID=MSC13,RMTPLKID=MSC,LCLIMS=(IMS1,IMS2),RMTIMS=IMS3,GENIMSID=IMS)
```
On the remote IMS system, specify one MSPLINK macro to define the TCP/IP physical link that will connect to the TCP/IP generic resource group.
Other than specifying the shared generic IMS ID on the NAME parameter, no special coding is required in the MSPLINK macro for TCP/IP generic resources. The remote IMS system is unaware that TCP/IP generic resources are used.
For example, the IMS system, IMS3, that is connecting to the TCP/IP generic resource group could code the following MSPLINK statement:
```
PLNK31TA MSPLINK
         NAME=IMS,
         LCLICON=HWS2,
         LCLPLKID=MSC,
         TYPE=TCPIP,
         SESSION=2
```
In the HWSCFGxx PROCLIB member of the remote IMS Connect instance, define an MSC configuration statement to correspond to the MSPLINK statement in IMS3.
Specify the shared generic IMS ID of the TCP/IP generic resource group on the RMTIMS parameter of the MSC statement. Specify the ID of the physical link from any MSPLINK macro in the TCP/IP generic resource group on the RMTPLKID parameter.

For example, if the ID of the physical link in the TCP/IP generic resource group is MSC13 in IMS1 and MSC23 in IMS2, you can specify either MSC13 or MSC23 on the RMTPLKID parameter of the MSC statement in the remote IMS Connect. In the following MSC statement MSC13 is specified:
```
MSC=(LCLPLKID=MSC,RMTPLKID=MSC13,LCLIMS=(IMS3),RMTIMS=IMS)
```

To determine if TCP/IP generic resources are active, you can issue the /DISPLAY ACT DC command.

After MSC TCP/IP generic resources are enabled, if the remote IMS system starts the link, the first IMS system in the TCP/IP generic resource group to respond to IMS Connect accepts the start request. After the link request is accepted, the logical link has affinity to the IMS system that accepted the link request.

If a logical link is started from an IMS system within the TCP/IP generic resource group, the link has affinity with the specific IMS system from which the link was started.

A logical link with affinity cannot be moved to another IMS system without terminating all logical links on the physical link.

You can control which IMS system in a TCP/IP generic resource group accepts a link request by stopping logons to the physical link in all IMS systems in the group, except in the one IMS system with which affinity is required. The following commands stop logons to physical links on IMS systems in a TCP/IP generic resource group:

The IMS type-2 command UPDATE MSPLINK NAME(linkname) STOP(GENLOGON)
The IMS type-1 command /PSTOP MSPLINK

After affinity has been established, you can confirm which IMS system has affinity by issuing any of the following commands:

/DISPLAY AFFIN LINK
QUERY IMS
QUERY MSLINK

The following figure shows the TCP/IP generic resource group defined by the preceding example definitions.

Figure shows an IMSplex with a TCP/IP generic resource group comprised of two IMS systems that is connected to a remote IMS system by a local IMS Connect instance and a remote IMS Connect instance. The required configuration statements are contained in the preceding text.